Spatial light modulators are arrays of one or more devices that can control or modulate an incident beam of light in a spatial pattern that corresponds to an electrical input to the devices. The incident light beam can be modulated in intensity, phase, polarization or direction. The majority of spatial light modulators are intensity modulators (often intensity modulation causes some phase modulation, but the phase modulation cannot be done independently to the intensity modulation). Some modulation can be accomplished through the use of Micro-ElectroMechanical System devices (or MEMS) that use electrical signals to move micromechanical structures to modulate light incident thereon.